Isosurface is a surface of equal value of a scalar field. Here you can view a seismic anomaly isosurface in 3-D. Choose a model below and a number on the right scrollbar. The first numbers bring up a picture for the "stronger anomaly" isosurfaces. It typically starts at an anomaly of a 1 or 2 percents of the seismic velocity and reduces down to 0.2-0.5 persents. The blue color represent colder anomaly, and the red is hotter. At step 5 (number on the right scrollbar), the image shows the weakest anomaly available for the analysis here. Any next step would rotate the image to view this weakest anomaly isosurface from different angles.
Press "Movie" to see the whole sequence of the isosurfaces and their rotation.

choose a model -> ?........?........?........?

and a snap shot -> ?......?

3D isosurfaces at various % anomaly